Reciprocating piston type compressors typically employ suction and discharge pressure actuated valve assemblies mounted onto a valve plate assembly which is located at end of a cylinder defined by a compressor body. The valve plate assembly is typically sandwiched between a compressor head and the body of the compressor. A valve plate gasket is located between the valve plate assembly and the compressor body to seal this interface and a head gasket is located between the valve plate assembly and the compressor head to seal this interface.
The discharge valve assembly typically includes a discharge valve member which engages a valve seat defined by the valve plate assembly, a discharge valve retainer to attach the discharge valve member to the valve plate assembly and a discharge spring which is disposed between the discharge valve member and the discharge valve retainer to bias the discharge valve member into engagement with the valve seat defined by the valve plate assembly.
An important design objective for the reciprocating compressor is to minimize the re-expansion or clearance volume in the cylinder when the piston reaches top dead center. The minimizing of this re-expansion or clearance volume helps to maximize the capacity and efficiency of the reciprocating compressor. In order to minimize this re-expansion or clearance volume, the valving system and the cylinder top end wall should have a shape which is complimentary with the shape of the piston to enable the piston to reduce the volume of the compression chamber to a minimum when the piston is at top dead center of its stroke without restricting gas flow. While it may be possible to accomplish this objective by designing a complex piston head shape, manufacturing of this complex shape becomes excessively expensive, the assembly becomes more difficult and throttling losses generally occur as the piston approaches top dead center.
Prior art suction valve assemblies and discharge valve assemblies have been developed to meet the above defined design criteria relating to re-expansion or clearance volume and these valve assemblies have performed satisfactory in the prior art compressors.
One area that can provide additional benefits to the reciprocating piston type compressors is in the area of compressed gas flow. As the piston begins its compression stroke, the gas within the compression chamber is compressed and eventually the discharge valve assembly opens to allow the compressed gas to flow into the discharge chamber. The compressed gas must flow past all of the components of the discharge valve assembly and thus the design of these components are critical to ensure that the flow of compressed gas is not restricted and therefore any throttling losses are reduced or eliminated.
The present invention provides the art with a unique design for the discharge valve retainer which improves gas flow to minimize and/or eliminate throttling losses associated with the compressed gas flow. The discharge valve retainer of the present invention is manufactured using a powder metal process utilizing a retainer material and density that define and optimize the retainer's structural, reliability and performance. In addition, the geometry of the discharge valve retainer has been optimized to deliver the best performance.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.